A roaring waterfall serves as the main backdrop for this stage. Mega Man will race along in front of it, then drop down to its base for some underwater encounters. This is one of my favorite stages in the series history, and it also happens to be a piece of cake now that you've acquired the Metal Blades.

Start by heading to the right. You're on a series of wide, white ledges, and the only enemies are giant frogs that sound out little versions of themselves to attack. They send three at a time, and will send more whenever those first three are out of commission (either because you've shot them, or because they foolishly leaped to their own doom). Metal Blades work wonders here, and you can even throw them diagonally if necessary. When you leap to the fifth and final ledge, press quickly to the right, even though you'll likely take a hit. This is preferable to standing along the edge and taking a hit from a miniature frog that knocks you backward off the ledge and to your death.

When you've taken out the third and final frog, continue on to a series of red-colored ledges. They look almost like logs floating against the backdrop. Hop quickly across them in one set of jumps. If you hesitate, you'll end up falling to your death; the ledges can only sustain your weight for the merest fraction of a second (though it is possible to quickly hop across the whole set of them without causing even one of them to fall, if you're particularly light-footed).

Once you've crossed that series of jumps, you'll have no choice but to continue right, then drop down to the next screen below. The hermit crabs here are actually taken out most easily with arm cannon shots. Hit them with Metal Blade shots and you'll have to use multiple hits. If you have the Metal Blade still equipped (and you likely should), avoiding them is almost easier. They don't move very quickly.

Beyond the first screen of hermit crabs, you'll drop down to another, then another. This one happens to be underwater. Note that when Mega Man is underwater, a normal jump carries him to the very top of the screen! This is important to keep in mind at all times, as you'll find in a moment. Drop down to the next screen and head to the right. The ceiling is now lined with spiked barbs. Just brushing them kills Mega Man instantly, so pay careful attention to how hard you tap the 'A' button as you head to the right.

The first hazard you'll come to (other than the spikes) is a giant lantern fish that sends out squid. You can kill any of the squid with a single shot from the Metal Blades you're packing, but the fish itself is only vulnerable if struck in the lantern. Hit it with five or six Metal Blades and the giant fish will explode, allowing you to proceed.

Next you must navigate a series of ledges, while robotic jellyfish rain down from above. They aren't your main concern, however. Instead, you should continue to take note of the spikes. Because the ledges vary in elevation, the safest technique is to cross the various ones, drop into a recess, then tackle the next ledge. If you attempt them one at a time, you'll do better. Trying to drop diagonally from one ledge to a shorter one just ahead usually ends up with Mega Man brushing against a spike and heading back to the stage's checkpoint, just before the lantern fish.

Speaking of the lantern fish, you'll encounter one just beyond the jellyfish, after dropping through a narrow, spike-lined area. The strategy here is the same as before, with the added hazard of spikes to the left. You should do just fine if you focus, and beyond the second fish you'll find two more of the giant frogs. Their little minions swim, now that they're underwater, but the battle technique is mostly the same.

Past the frogs, you finally emerge from the dangerous water, and are back at the waterfall. It's still easy to die, however, as you cross a final series of ledges. The problem here is that crabs are falling from the sky. Wait for them to fall and quickly take them out with Metal Blades before hopping from one ledge to the next, or you may very well end up knocked into a bottomless pit. Across this series of ledges and gaps, you'll find the gate leading to the area's robot master.

Bubble Man

With a fish net behind him and spikes lining the ceiling, Bubble Man must feel pretty confident. Shake that confidence with a few shots from the Quick Boomerang. Around six shots will do him in, as he glides around the screen sending bubbly harpoons at Mega Man.

If you're using the arm cannon instead of the boomerang, note that you'll want to jump in the air slightly after Bubble Man makes a leap, so that all his shots pass over your head but you get in some shots of your own. It will take quite a few shots from the arm cannon, but the battle is still quite simple. Alternatively, you can use the Metal Blades and throw them diagonally as your nemesis glides about the area. They work almost as well as the Quick Boomerang. When you win the encounter, you'll get one of the most important items in the game, the Bubble Lead.